Disclaimer!!! This thread is for reference only!! I take no responsibility for any damage you cause if you try this!

So let's get started:

Remove lower dash panel and then remove the airbag fuse

Remove Negative Battery Connection

Remove Ignition trim cover screw. There is only 1

Separate the upper and lower trim covers. This is done by pushing back on the bottom cover while pulling forward and up on the top. This step is a little tricky. There are tabs that catch on the front. You need to disconnect these by pushing the bottom back.

Remove the key FOB interface from the cylinder. Disconnect wires from the interface first. The unit just slides off the cylinder.

Remove the ignition cylinder. This is done by turning the key to the ON position and insert a small Allen or drill bit into the hole on top of the cylinder. When you push down the tab inside the cylinder, you will be able to turn the key slightly and remove the entire cylinder assembly.

Cylinder Disassembly. Turn the key until you are fully on. Push down the pin and turn the key further to release the pin. Be ready to catch it. It's pretty clear where it is going to become unretained. There is a small spring behind it, don't lose it. At this time, you can slide the tumbler assembly out from the cylinder. There is a small black guide that may or may not fall out. If it does, there is a tiny spring behind it. Don't lose that either.

Note: I have never removed my key from the tumbler assembly when it was out of the cylinder. If you remove your key, the tumblers may fall out, or they might not. I never tired. Try at your own risk.

Here you can see the previous step completed. You will see the black tab is removed. He fits in that slot on the top near the key. The spring goes along side. It's easy to put back together, just don't lose anything.

Now to understand the problem: This pin, shown below, fits into this slot when the key is off. Normally when you go to turn the key, it will follow the ramp out of the slot and onto the main track. The problem is that a rut has developed at the bottom of the ramp. The pin is hanging up in this rut.

My solution was to CAREFULLY smooth out this ramp with a Dremel tool to remove the rut. I basically changed the profile of the ramp so the pin would move nice and easy. Take your time, remove the smallest amount of material possible and then clean all the dust out. Once I had the entire assembly clean, I cleaned the tumblers the best I could as well. After applying a good coat of grease to all moving surfaces, especially where the pin slides on the ramp, I reassembled. Last, reinstall into the car and put everything back together.

At this time, my ignition is totally smooth and works like it's new. Granted my problem wasn't quite as advanced as some other people, but this fixed my sticking issue. If you are considering this project, take your time and understand what the problem is when you have the cylinder in your hand. Once you know what is causing the problem you will have a better chance fixing it.

From 1qwkgoat : Upon putting the key cylinder back into the column. Mine would no go all the way in and lock. I found the there was a piece inside the hole where the cylinder goesn that was U shaped(from what I could see). That had to be moved down(towards the foor) and then my key cylinder went right in. Not sure if anybody elses car has been like this. Just thought I let everyone know. Because it frustrated me to no end for about 10 min until I figured it out.
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This should be added to the knowledge base. Very important point you make here. I had this problem and wish I had read this first. Simply look for the square tab inside and push down until it clicks, then your ready to install the lock.
I ended up breaking the lock latch that hold the whole thing in. Had to buy a new lock kit from GM for $47 bucks. But I got it working that day by just taking out the little broken piece and using the other half with the spring. Looks like that piece cannot be